Reverse osmosis systems (referred to alternatively herein as "R/O" Systems) applied to the purification of water are known in the art. Their use is expanding rapidly for the production of relatively small quantities of potable water for household uses.
Such reverse osmosis systems under normal operating conditions produce a continuous flow of waste water, which may amount to as much as 75% of the input water volume, and which may have a high salt content. This waste water or brine must have a continuous drainage facility for removing this processed water from the reverse osmosis system. In this respect, for the safety of the system and to meet laws and ordinances of towns and municipalities, particularly where such drainage facilities are connected to the sewer system, an adequate anti-syphon means is required to prevent the possibility of sewage or tainted water backing into the R/O System through the drain for the waste water or brine. Generally this is in the form of an air gap in the drain line at a specified height above the waste water basin overflow plane for undercounter installation set-ups.
Typically, most kitchen counter single compartment sinks have their sole bottom outlet plumbed directly to the main waste inlet of a conventional garbage disposer unit. Waste water from the sink flows through the garbage disposer and exists horizontally via an outlet plumbing elbow, provided with and attached to the disposer at its lower side, which leads through a 90.degree. bend vertically downwardly into the upper inlet end of a standard plastic or brass tubular plumbing trap. The disposer may also have a dishwasher drain line connected into a disposer inlet nipple in the upper side thereof and that feeds waste water from the dishwasher through the disposer and out of the disposer outlet.
Hitherto, a serious problem has existed with respect to undercounter R/O Systems installations, particularly retrofit installations, with respect to the manner and means for connecting the outlet end of the waste water drain line, downstream of the air gap, to the standard disposer drain plumbing fittings conventionally encountered in most household plumbing systems. Most plumbing codes (and R/O manufacturer's warranties) prohibit the connection of R/O waste water drain line anywhere in the outlet plumbing elbow of the disposer because of the danger of clogging by the relatively high velocity discharge from the disposer when the same is operated in the disposal grinding mode to grind and wash down garbage and similar refuse. Such codes also require the R/O waste water drain line to be connected upstream of a suitable sewer trap. Hence in the case of single compartment, disposer-equipped sinks there may be no alternative (except for using the adapter coupler invention disclosed in my co-pending parent application Ser. No. 08/206,850 filed Mar. 7, 1994, incorporated herein by reference, now U.S. Pat. No. 5,449,456) for the R/O System installer but to run the R/O waste water drain line down through the kitchen floor to a laundry sink standpipe or available basement or cellar floor drain or to install (if not already present) a conventional multi-port dishwasher air gap fixture which drains out into a dishwasher drain hose or a branch tailpiece. Of course, either of these prior art procedures is expensive and time consuming from the labor and material standpoint, and in some instances a suitable connection of this type may not be economically feasible or even available, thereby effectively preventing installation of the R/O System.
Even in those residential kitchen sink installations which are provided with a double compartment sink, certain installation problems remain. In such double sink installations one of the sinks or sink compartments carries the garbage disposer, and the other, non-disposer sink, has its waste water outlet connected via standard plumbing fittings, which includes a horizontal outlet run leading into a conventional baffle Tee-fitting connected between the disposer elbow and sink drain trap (or to its own trap). This disposer Tee has an interior baffle which operates to divert the downward discharge from the disposer elbow away from and past the Tee-inlet connected to the non-disposer sink plumbing. Plumbing codes permit the R/O waste water drain line connection to enter such non-disposer sink waste plumbing upstream of the disposer baffle Tee because of the isolation provided by its interior baffle. Accordingly, commercially available R/O System installation equipment often includes conventional drain saddle hardware fittings, i.e., split clamp straps, mounting fasteners and an associated drain saddle elbow for making this waste water drain connection to such existing plumbing fittings. However, this requires that a suitable hole be drilled into either the vertical or horizontal run of the non-disposer sink outlet plumbing fittings, and the drain saddle clamp fitting registered and clamped to communicate the elbow with the drilled hole.
Although kitchen double compartment sinks thus can physically accommodate connection of the R/O waste water drain line upstream of the disposer baffle Tee and in the immediate vicinity of the undercounter R/O System installation, more and more state and local plumbing codes prohibit the use of saddle-type valves and/or drain connections. Indeed, current efforts are well underway or have been completed to ban saddle-type valve or drain connections in all fifty states. Hence in such states, even with a double compartment sink plumbing arrangement incorporating a disposer baffle Tee, the R/O waste water drain line outlet again must be run from under the kitchen counter to the basement or some other area having a standpipe or drain arranged to feed into a suitable entry point to the household sewer system, such as the aforementioned laundry sink standpipe or basement floor drain. Such waste water drain line connection problems have seriously impeded or prevented retrofit installations of R/O filter systems in existing dwelling structures, particularly in older residences and in well developed older communities supplied with municipal water, where such R/O water filter systems are particularly needed.